Grinding mill



Feb. 3, 925- 1,524,871

P. T. LINDHARD GRINDING MILL 'Filed June 28, 1922 4 sheets-Sheet 1 I .InYIIIIIIIIIIIIIIIIIIIIIIIIII WITNESS f) l/VI/ENTOR Br 3 {d ATTORNEYS Feb. 3, 1925. 1,524,871

P. "r. LINDHARD GRINDING MILL Filed June 28, 192 '4 Sheets-Sheet z ELQIZ. w

P. T. LINDHARD Feb. 3, 192

GRINDING MILL Filed June 28, 1922 4 Sheets-Sheet 3 Feb. 3, 1925- 1.524.871

' P. T. LINDHARD GRINDING MILL Filed June 1922 4 sheets-Sheet 4.

WITNESS INVENTOR.

I 4%% v PM Q BY 7 TTOH/VEYS Patented Feb. 3, 1925.

uNrrEu STATES,

PATENT oFFIca,

rovL rr. LINDHABID, or BROOKLYN, NEW YORK, ASSIGNQR TO r. L. smirrn: ace, or NEW'YORK, N. Y., ACORPORATIONOF NEW JERSEY.

GRINDING MILL.

I Application filed June 28, 1922. Serial No. 571,385.

1 0 at; whom it may concern Be itknownthat I,-PovL T. LINDHARI), a citizen of the United States, residing in -the borough of Brooklyn,in the city and State of New York, have invented "certain newand useful Improvements-in Grinding Mlle, of which the following is a specification, reference being had to the accompanying drawings, forming a part hereof.

In Letters Patent 'of the United. States No. 1,437,599, dated December 5, 1922, there are shown and described certain improvements ingrinding mills which are concerned more particularly with the provision of relatively great screening surface or area within a comparatively restricted space. The present invention is concerned with the construction of the, separators or screening devices and with the general internal construction of a grinding mill in which a screening or separating compartment is in terposed between two grinding compartments and in which provision is made for the grinding within the. screening or separating compartment of the'tailings which are retained therein as the finely ground material is separatedfrom such tailings. The invention will be explained more fully hereinafter with'reference to the accompanying drawings in which- Figure 1 is a view in longitudinal, central section, of the improved grinding mill.

Figures 2 and?) are detail views, in longitudinal section and transverse section respectively, and on a larger scale than that of Figure 1, illustrating one-form of construction of the screening devices. i

Figures 4 and 5- are views generally similar to Figures 2 and 3 but illustrating a slightly different form of construction.

Figures 6 and 7 and Figures 8 and 9 are detail views on a still larger scale, illustrating two other forms of construction.

In the embodiment of the invention illustrated in Figure 1, a generally cylindrical shell a, of usual construction except as hereinafter indicated, mounted and rotated in usualmanner,'is provided at one end with an inlet or feed head 0 and at the other end with an outlet or discharge head d. It is shown as comprising a primary grinds ing chamber e, provided in the usual manner with grinding bodies e and a'lining e a secondary grinding chamber 7, also pro- I vided with grinding bodies f and a lining f and an intermediate screening or separatlng compartment g. A lifting partition it, of the usual construction, having the usual radial vanes or ribs h, by which the material is lifted, and the usual cone 72 by which the material discharged by the vanes is directed through the central open.- ing in the second Wall into the succeeding compartment, interposed between the primary grinding compartment e and the separating compartment g, is arranged to deliver from the primary grindingcompartment 6 'into'the separating compartment the material which has been partly ground in the primary grinding compartmente. A lifting partition in, also of ordinary construction, is disposed between the separating compartment 9 and the secondary grinding compartment and is arranged in usual 'manner to deliver the material, which has already been partly reduced in the compartment 6 and separated in the compartment 9 from the tailings, into the secondary grinding compartment f where it receives a further grinding.

The grinding compartment gf'is provided with one or more screens or separators n which. may be constructed as hereinafter described, although not necessarily so, and with an inner shell g,- of smaller diameter than the shell a so that there is formed, between the two shells a receiving and conveying space 0, which may be fitted with spiral conveyorsvo', by which the partially reduced material'which is separated, in the separating chamber, from the tailings, is passed onto the secondary grinding compartment." In order that the reduction of the tailings in the separating compartment may be continued, theseparating compartment is provided with a lining g and with grinding bodies 9 1 1 So far as the general construction and arrangement of the grinding mill are con undue expansion of the separating compart- In the construction shown in Figures 2 and 3 the separating compartment 9 is secured in place by bolts n, which shown as provided'with two screens or separators, each of which is annular, surrounding an open center, and is made up of a series of cages a, each of which is made up of a frame a and two members a perforated as at n, the cage members being pass throu h the linin g of the shell -g, bear-' ing b ocks 0 an. the outer shell 0. The

members n of each cage maybe further secured together. by bolts a. Eachseparator unit or cage n has a free opening between its members 12,, adjacent the shell g, which registers with an opening 9 throu h the lining and the. inner shell so that t e finer material, which passes through the perforated side walls of the separator units, shall pass freely into the receiving and conveying space 0, between the shells a and g, and be caused by the .conveyero to'pass 'onward until it reachesthe lifting partition h and is thereby transferred. to the sec- .ondary grinding compartment 7.

In the construction of the separating devices shown in Figures 4 and 5, the separator units n? are formed as already described with respect to Figures 2 and 3.. The inner shell 9 is shown as having the conveyor plates 0 formed integrally therewith and bearing directly against-the outer shell a. In this instance the bearing blocks are dispensed with, the bolts a passing throu h the inner shell 9 and the outer shella. penings g are formed in the shell 9 as previously described, to permit the finer material to pass from between the perforated side walls of the separator units into the receivin and conveying space 0 between the two. s ells, through which it is conveyed, as before, to

the lifting artition h by which it is trans ferred to t e secondary grinding compartment f, while the tailings, retained within the separating compartment, are. further reduced by the grinding bodies 9? with which the separating compartment is charged.

In the construction shown in Figures 6 and 7 each separating unit 127, having perforated side walls as before, is shown as formed as a single casting provided 'with.

notched flanges n, for engagement b bolts n", which are in turn engaged with a anged frame a, riveted, as indicated at n, to the inner shell g around the opening g,

through which, the separator unit is passed from the outside of t e shell. In this construction the finer material, which passes through the. perforated walls of the separator unit, passes into the space 0 between the inner and outer shells and then is trans ferred as previously described, to the lift 'ing partition It, by which it is transferred to the secondary grinding'compartment f.

The construction illustrated in Figures 8 and 9 is substantially like that illustrated in Figures 6 and 7 exceptthat each'separator unit n.- is passed from the oustide of the shell a through an opening a therein and through an opening 9 in the shell g, the

separator t ving open ends, as at n 3,

separating devices, suitable for use in a mill ofthe character. of that indicated herein, will readily ,suggest themselves and it will be understo that except as pointed out in the claims, the invention is not. restricted to the particular construction shown and described herein.

I claim as my invention: 1; A grinding mill comprising a rotatable shell, two lifting partition disposed in the Oil shell and forming a primary grinding compartment, a secondary grinding compartment and'an interposed separating compartment, said separating compartment having an inner shell separated from the first mentioned shell to form a receiving and conveying space between the two, the inner shell having openings therethrough, and a separating device disposed in the separating compartment and arran' ed to deliver the finer material through t e opening in the inner shell into the receiving and conveying space between the two shell i 2. In a grinding-.mill, the combination of an outer shell, an inner shell separated from the outer shell to form a receiving and com veying space and havingan opening there? through and a separating cage secured ;in "position'with its open end in registration with the opening through the inner shell.

3. In a grinding mill the-combination of an outer shell,'an inner shell separated from the outer shell t'o form a receiving and con veying space and having openings therethrough and an annular series of separating cages secured in position with their open ends in re 'stration with the openings through the inner shell.

4. n a grinding mill the combination of an outer imperforate shell, an inner shell having an opening therethrough, a separator cage having opposite per orated walls with a free opening betweenthemfor registration with the opening'through the shell,

and means to secure the cage in position in the walls for registration with the openin s 'relation to the shell. through the shell, and means to secure tfie 5. In a grinding mill the combination of se arator ca es in relation to the shell. 10 an outer imperforate shell, an inner shell his speci 'cation signed this 17th day of 5 having openings therethrough, an annular June, A. D. 1922.

series of separator cages having opposite perforated walls with free openings between POVL T. LINDHARD. 

